fs_initcall(init_dax_wait_table);
/*
- * We use lowest available bit in exceptional entry for locking, one bit for
- * the entry size (PMD) and two more to tell us if the entry is a zero page or
- * an empty entry that is just used for locking. In total four special bits.
+ * DAX pagecache entries use XArray value entries so they can't be mistaken
+ * for pages. We use one bit for locking, one bit for the entry size (PMD)
+ * and two more to tell us if the entry is a zero page or an empty entry that
+ * is just used for locking. In total four special bits.
*
* If the PMD bit isn't set the entry has size PAGE_SIZE, and if the ZERO_PAGE
* and EMPTY bits aren't set the entry is a normal DAX entry with a filesystem
* block allocation.
*/
-#define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 4)
-#define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT)
-#define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1))
-#define RADIX_DAX_ZERO_PAGE (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2))
-#define RADIX_DAX_EMPTY (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 3))
+#define DAX_SHIFT (4)
+#define DAX_LOCKED (1UL << 0)
+#define DAX_PMD (1UL << 1)
+#define DAX_ZERO_PAGE (1UL << 2)
+#define DAX_EMPTY (1UL << 3)
static unsigned long dax_radix_pfn(void *entry)
{
- return (unsigned long)entry >> RADIX_DAX_SHIFT;
+ return xa_to_value(entry) >> DAX_SHIFT;
}
static void *dax_radix_locked_entry(unsigned long pfn, unsigned long flags)
{
- return (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | flags |
- (pfn << RADIX_DAX_SHIFT) | RADIX_DAX_ENTRY_LOCK);
+ return xa_mk_value(flags | ((unsigned long)pfn << DAX_SHIFT) |
+ DAX_LOCKED);
}
static unsigned int dax_radix_order(void *entry)
{
- if ((unsigned long)entry & RADIX_DAX_PMD)
+ if (xa_to_value(entry) & DAX_PMD)
return PMD_SHIFT - PAGE_SHIFT;
return 0;
}
static int dax_is_pmd_entry(void *entry)
{
- return (unsigned long)entry & RADIX_DAX_PMD;
+ return xa_to_value(entry) & DAX_PMD;
}
static int dax_is_pte_entry(void *entry)
{
- return !((unsigned long)entry & RADIX_DAX_PMD);
+ return !(xa_to_value(entry) & DAX_PMD);
}
static int dax_is_zero_entry(void *entry)
{
- return (unsigned long)entry & RADIX_DAX_ZERO_PAGE;
+ return xa_to_value(entry) & DAX_ZERO_PAGE;
}
static int dax_is_empty_entry(void *entry)
{
- return (unsigned long)entry & RADIX_DAX_EMPTY;
+ return xa_to_value(entry) & DAX_EMPTY;
}
/*
*/
static inline int slot_locked(struct address_space *mapping, void **slot)
{
- unsigned long entry = (unsigned long)
- radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock);
- return entry & RADIX_DAX_ENTRY_LOCK;
+ unsigned long entry = xa_to_value(
+ radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock));
+ return entry & DAX_LOCKED;
}
/*
*/
static inline void *lock_slot(struct address_space *mapping, void **slot)
{
- unsigned long entry = (unsigned long)
- radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock);
-
- entry |= RADIX_DAX_ENTRY_LOCK;
- radix_tree_replace_slot(&mapping->i_pages, slot, (void *)entry);
- return (void *)entry;
+ unsigned long v = xa_to_value(
+ radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock));
+ void *entry = xa_mk_value(v | DAX_LOCKED);
+ radix_tree_replace_slot(&mapping->i_pages, slot, entry);
+ return entry;
}
/*
*/
static inline void *unlock_slot(struct address_space *mapping, void **slot)
{
- unsigned long entry = (unsigned long)
- radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock);
-
- entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK;
- radix_tree_replace_slot(&mapping->i_pages, slot, (void *)entry);
- return (void *)entry;
+ unsigned long v = xa_to_value(
+ radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock));
+ void *entry = xa_mk_value(v & ~DAX_LOCKED);
+ radix_tree_replace_slot(&mapping->i_pages, slot, entry);
+ return entry;
}
/*
* Lookup entry in radix tree, wait for it to become unlocked if it is
- * exceptional entry and return it. The caller must call
+ * a DAX entry and return it. The caller must call
* put_unlocked_mapping_entry() when he decided not to lock the entry or
* put_locked_mapping_entry() when he locked the entry and now wants to
* unlock it.
*
* Must be called with the i_pages lock held.
*/
-static void *get_unlocked_mapping_entry(struct address_space *mapping,
- pgoff_t index, void ***slotp)
+static void *__get_unlocked_mapping_entry(struct address_space *mapping,
+ pgoff_t index, void ***slotp, bool (*wait_fn)(void))
{
void *entry, **slot;
struct wait_exceptional_entry_queue ewait;
ewait.wait.func = wake_exceptional_entry_func;
for (;;) {
+ bool revalidate;
+
entry = __radix_tree_lookup(&mapping->i_pages, index, NULL,
&slot);
if (!entry ||
- WARN_ON_ONCE(!radix_tree_exceptional_entry(entry)) ||
+ WARN_ON_ONCE(!xa_is_value(entry)) ||
!slot_locked(mapping, slot)) {
if (slotp)
*slotp = slot;
prepare_to_wait_exclusive(wq, &ewait.wait,
TASK_UNINTERRUPTIBLE);
xa_unlock_irq(&mapping->i_pages);
- schedule();
+ revalidate = wait_fn();
finish_wait(wq, &ewait.wait);
xa_lock_irq(&mapping->i_pages);
+ if (revalidate)
+ return ERR_PTR(-EAGAIN);
}
}
-static void dax_unlock_mapping_entry(struct address_space *mapping,
- pgoff_t index)
+static bool entry_wait(void)
+{
+ schedule();
+ /*
+ * Never return an ERR_PTR() from
+ * __get_unlocked_mapping_entry(), just keep looping.
+ */
+ return false;
+}
+
+static void *get_unlocked_mapping_entry(struct address_space *mapping,
+ pgoff_t index, void ***slotp)
+{
+ return __get_unlocked_mapping_entry(mapping, index, slotp, entry_wait);
+}
+
+static void unlock_mapping_entry(struct address_space *mapping, pgoff_t index)
{
void *entry, **slot;
xa_lock_irq(&mapping->i_pages);
entry = __radix_tree_lookup(&mapping->i_pages, index, NULL, &slot);
- if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry) ||
+ if (WARN_ON_ONCE(!entry || !xa_is_value(entry) ||
!slot_locked(mapping, slot))) {
xa_unlock_irq(&mapping->i_pages);
return;
static void put_locked_mapping_entry(struct address_space *mapping,
pgoff_t index)
{
- dax_unlock_mapping_entry(mapping, index);
+ unlock_mapping_entry(mapping, index);
}
/*
for (pfn = dax_radix_pfn(entry); \
pfn < dax_radix_end_pfn(entry); pfn++)
-static void dax_associate_entry(void *entry, struct address_space *mapping)
+/*
+ * TODO: for reflink+dax we need a way to associate a single page with
+ * multiple address_space instances at different linear_page_index()
+ * offsets.
+ */
+static void dax_associate_entry(void *entry, struct address_space *mapping,
+ struct vm_area_struct *vma, unsigned long address)
{
- unsigned long pfn;
+ unsigned long size = dax_entry_size(entry), pfn, index;
+ int i = 0;
if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
return;
+ index = linear_page_index(vma, address & ~(size - 1));
for_each_mapped_pfn(entry, pfn) {
struct page *page = pfn_to_page(pfn);
WARN_ON_ONCE(page->mapping);
page->mapping = mapping;
+ page->index = index + i++;
}
}
WARN_ON_ONCE(trunc && page_ref_count(page) > 1);
WARN_ON_ONCE(page->mapping && page->mapping != mapping);
page->mapping = NULL;
+ page->index = 0;
}
}
return NULL;
}
+static bool entry_wait_revalidate(void)
+{
+ rcu_read_unlock();
+ schedule();
+ rcu_read_lock();
+
+ /*
+ * Tell __get_unlocked_mapping_entry() to take a break, we need
+ * to revalidate page->mapping after dropping locks
+ */
+ return true;
+}
+
+bool dax_lock_mapping_entry(struct page *page)
+{
+ pgoff_t index;
+ struct inode *inode;
+ bool did_lock = false;
+ void *entry = NULL, **slot;
+ struct address_space *mapping;
+
+ rcu_read_lock();
+ for (;;) {
+ mapping = READ_ONCE(page->mapping);
+
+ if (!dax_mapping(mapping))
+ break;
+
+ /*
+ * In the device-dax case there's no need to lock, a
+ * struct dev_pagemap pin is sufficient to keep the
+ * inode alive, and we assume we have dev_pagemap pin
+ * otherwise we would not have a valid pfn_to_page()
+ * translation.
+ */
+ inode = mapping->host;
+ if (S_ISCHR(inode->i_mode)) {
+ did_lock = true;
+ break;
+ }
+
+ xa_lock_irq(&mapping->i_pages);
+ if (mapping != page->mapping) {
+ xa_unlock_irq(&mapping->i_pages);
+ continue;
+ }
+ index = page->index;
+
+ entry = __get_unlocked_mapping_entry(mapping, index, &slot,
+ entry_wait_revalidate);
+ if (!entry) {
+ xa_unlock_irq(&mapping->i_pages);
+ break;
+ } else if (IS_ERR(entry)) {
+ WARN_ON_ONCE(PTR_ERR(entry) != -EAGAIN);
+ continue;
+ }
+ lock_slot(mapping, slot);
+ did_lock = true;
+ xa_unlock_irq(&mapping->i_pages);
+ break;
+ }
+ rcu_read_unlock();
+
+ return did_lock;
+}
+
+void dax_unlock_mapping_entry(struct page *page)
+{
+ struct address_space *mapping = page->mapping;
+ struct inode *inode = mapping->host;
+
+ if (S_ISCHR(inode->i_mode))
+ return;
+
+ unlock_mapping_entry(mapping, page->index);
+}
+
/*
- * Find radix tree entry at given index. If it points to an exceptional entry,
- * return it with the radix tree entry locked. If the radix tree doesn't
- * contain given index, create an empty exceptional entry for the index and
- * return with it locked.
+ * Find radix tree entry at given index. If it is a DAX entry, return it
+ * with the radix tree entry locked. If the radix tree doesn't contain the
+ * given index, create an empty entry for the index and return with it locked.
*
- * When requesting an entry with size RADIX_DAX_PMD, grab_mapping_entry() will
+ * When requesting an entry with size DAX_PMD, grab_mapping_entry() will
* either return that locked entry or will return an error. This error will
* happen if there are any 4k entries within the 2MiB range that we are
* requesting.
xa_lock_irq(&mapping->i_pages);
entry = get_unlocked_mapping_entry(mapping, index, &slot);
- if (WARN_ON_ONCE(entry && !radix_tree_exceptional_entry(entry))) {
+ if (WARN_ON_ONCE(entry && !xa_is_value(entry))) {
entry = ERR_PTR(-EIO);
goto out_unlock;
}
if (entry) {
- if (size_flag & RADIX_DAX_PMD) {
+ if (size_flag & DAX_PMD) {
if (dax_is_pte_entry(entry)) {
put_unlocked_mapping_entry(mapping, index,
entry);
true);
}
- entry = dax_radix_locked_entry(0, size_flag | RADIX_DAX_EMPTY);
+ entry = dax_radix_locked_entry(0, size_flag | DAX_EMPTY);
err = __radix_tree_insert(&mapping->i_pages, index,
dax_radix_order(entry), entry);
if (index >= end)
break;
- if (WARN_ON_ONCE(
- !radix_tree_exceptional_entry(pvec_ent)))
+ if (WARN_ON_ONCE(!xa_is_value(pvec_ent)))
continue;
xa_lock_irq(&mapping->i_pages);
xa_lock_irq(pages);
entry = get_unlocked_mapping_entry(mapping, index, NULL);
- if (!entry || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry)))
+ if (!entry || WARN_ON_ONCE(!xa_is_value(entry)))
goto out;
if (!trunc &&
(radix_tree_tag_get(pages, index, PAGECACHE_TAG_DIRTY) ||
return ret;
}
/*
- * Delete exceptional DAX entry at @index from @mapping. Wait for radix tree
- * entry to get unlocked before deleting it.
+ * Delete DAX entry at @index from @mapping. Wait for it
+ * to be unlocked before deleting it.
*/
int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
{
* This gets called from truncate / punch_hole path. As such, the caller
* must hold locks protecting against concurrent modifications of the
* radix tree (usually fs-private i_mmap_sem for writing). Since the
- * caller has seen exceptional entry for this index, we better find it
+ * caller has seen a DAX entry for this index, we better find it
* at that index as well...
*/
WARN_ON_ONCE(!ret);
}
/*
- * Invalidate exceptional DAX entry if it is clean.
+ * Invalidate DAX entry if it is clean.
*/
int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
pgoff_t index)
{
void *vto, *kaddr;
pgoff_t pgoff;
- pfn_t pfn;
long rc;
int id;
return rc;
id = dax_read_lock();
- rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, &pfn);
+ rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, NULL);
if (rc < 0) {
dax_read_unlock(id);
return rc;
if (dirty)
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
- if (dax_is_zero_entry(entry) && !(flags & RADIX_DAX_ZERO_PAGE)) {
+ if (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE)) {
/* we are replacing a zero page with block mapping */
if (dax_is_pmd_entry(entry))
unmap_mapping_pages(mapping, index & ~PG_PMD_COLOUR,
new_entry = dax_radix_locked_entry(pfn, flags);
if (dax_entry_size(entry) != dax_entry_size(new_entry)) {
dax_disassociate_entry(entry, mapping, false);
- dax_associate_entry(new_entry, mapping);
+ dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address);
}
if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
* A page got tagged dirty in DAX mapping? Something is seriously
* wrong.
*/
- if (WARN_ON(!radix_tree_exceptional_entry(entry)))
+ if (WARN_ON(!xa_is_value(entry)))
return -EIO;
xa_lock_irq(pages);
entry2 = get_unlocked_mapping_entry(mapping, index, &slot);
/* Entry got punched out / reallocated? */
- if (!entry2 || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry2)))
+ if (!entry2 || WARN_ON_ONCE(!xa_is_value(entry2)))
goto put_unlocked;
/*
* Entry got reallocated elsewhere? No need to writeback. We have to
{
const sector_t sector = dax_iomap_sector(iomap, pos);
pgoff_t pgoff;
- void *kaddr;
int id, rc;
long length;
return rc;
id = dax_read_lock();
length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
- &kaddr, pfnp);
+ NULL, pfnp);
if (length < 0) {
rc = length;
goto out;
{
struct inode *inode = mapping->host;
unsigned long vaddr = vmf->address;
- vm_fault_t ret = VM_FAULT_NOPAGE;
- struct page *zero_page;
- pfn_t pfn;
+ pfn_t pfn = pfn_to_pfn_t(my_zero_pfn(vaddr));
+ vm_fault_t ret;
- zero_page = ZERO_PAGE(0);
- if (unlikely(!zero_page)) {
- ret = VM_FAULT_OOM;
- goto out;
- }
+ dax_insert_mapping_entry(mapping, vmf, entry, pfn,
+ DAX_ZERO_PAGE, false);
- pfn = page_to_pfn_t(zero_page);
- dax_insert_mapping_entry(mapping, vmf, entry, pfn, RADIX_DAX_ZERO_PAGE,
- false);
ret = vmf_insert_mixed(vmf->vma, vaddr, pfn);
-out:
trace_dax_load_hole(inode, vmf, ret);
return ret;
}
pgoff_t pgoff;
long rc, id;
void *kaddr;
- pfn_t pfn;
rc = bdev_dax_pgoff(bdev, sector, PAGE_SIZE, &pgoff);
if (rc)
return rc;
id = dax_read_lock();
- rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr,
- &pfn);
+ rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr, NULL);
if (rc < 0) {
dax_read_unlock(id);
return rc;
ssize_t map_len;
pgoff_t pgoff;
void *kaddr;
- pfn_t pfn;
if (fatal_signal_pending(current)) {
ret = -EINTR;
break;
map_len = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size),
- &kaddr, &pfn);
+ &kaddr, NULL);
if (map_len < 0) {
ret = map_len;
break;
pfn = page_to_pfn_t(zero_page);
ret = dax_insert_mapping_entry(mapping, vmf, entry, pfn,
- RADIX_DAX_PMD | RADIX_DAX_ZERO_PAGE, false);
+ DAX_PMD | DAX_ZERO_PAGE, false);
ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
if (!pmd_none(*(vmf->pmd))) {
* is already in the tree, for instance), it will return -EEXIST and
* we just fall back to 4k entries.
*/
- entry = grab_mapping_entry(mapping, pgoff, RADIX_DAX_PMD);
+ entry = grab_mapping_entry(mapping, pgoff, DAX_PMD);
if (IS_ERR(entry))
goto fallback;
goto finish_iomap;
entry = dax_insert_mapping_entry(mapping, vmf, entry, pfn,
- RADIX_DAX_PMD, write && !sync);
+ DAX_PMD, write && !sync);
/*
* If we are doing synchronous page fault and inode needs fsync,
git.samba.org / sfrench / cifs-2.6.git / blobdiff